Nitro plastic propellants



United States Patent Ofiice 3,971,617 Patented Jan. 1, 1%63 3,671,617NETRO PLASTIC PROPELLANTS Henry B. Hass, West Lafayette, lnd., assignorto Purdue Research Foundation, West Lafayette, End, a corporation ofIndiana No Drawing. Fiied June 1, 1948, Ser. No. 30,512 14 Claims. (Cl.250-553) The present invention relates to solid propellants.

.More particularly, the invention relates to smokeless propellants andto unique nitro plastics which may be employed as the sole or majorthrust-producing component of such solid smokeless propellants of thetype utilized in rocket and other similar jet-propulsion type motorsdemandin g great power.

Following upon the rapid' development of jet-type motors, a great demandhas arisen for solid propellants which are useful as fuel therein.Because of the many exacting specifications which such a solidpropellant must fulfill, very few, if any, solid propellants havingsuitable characteristics have been available up to the present time.

The ideal solid propellant would exhibit the following characteristics.It should:

(1) Be solid and stable over the entire range of ambient temperatures of40 to +60 degrees centigrade and under pressures between about 300 and1500 pounds per square inch.

(2) Burn uniformly and have a low temperature coefiicient, i.e., itsburning rate increase with temperature should be as small as possible.

(3) Be composed of large grains and preferably of large molecules.

(4) Have a low pressure exponent, i.e., its increase in burning ratewith pressure increase should be as small as possible.

(5) Be substantially smokeless.

(6) Have a satisfactory oxygen balance, i.e., it should preferablypossess enough oxygen to burn all carbon to carbon dioxide and allhydrogen to Water.

(7) Not undergo deterioration upon storage.

(8) Possess a minimum of susceptibility to detonation under conditionsof employment and be stable upon heating.

(9) Not be hygroscopic.

(10) Have a high specific impulse.

Still other specifications are desirable, but these may be consideredsub-specifications of those enumerated above.

It has previously been proposed to use as solid fuels compositionsembodying cellulose nitrate, but with such compositions the temperaturecoetficient is undesirably high so that the rate of burning of the fuelis relatively slow when cold and quite rapid when hot. While the rate atintermediate temperatures is satisfactory, it is impossible to maintainsuch desirable temperatures for any extended period. Further, cellulosenitrate is inherently unstable, and thus fails to fulfill another veryimportant requirement.

These disadvantages have been partially overcome with the provision ofcompositions embodying ethyl cellulosecastor oil, neoprene castingcements, cross-linked maleic anhydride-styrene resins, or otherstyrene-linear polyester resins or peptized gums, in admixture withperchlorate powders. However, with perchlorates, shorting of electricalequipment and corrosion is commonly experienced, and the white potassiumchloride smoke which comprises approximately 57 percent of the exitgases when potassium perchlorate is used limits visibility to anundesirable and hazardous extent. Likewise, when ammonium perchlorate isemployed, the mist-forming hydrogen chloride present in the exhaustgases is objectionable for the same reasons.

It is an object of the present invention to provide novel solidpropellants which are more suitable than previously known propellants. Afurther object of the invention is the provision of novel solidpropellants which are substantially smokeless. Another object of theinvention is the provision of novel solid propellants comprising a nitroplastic having a minimum oxygen balance of minus 80. Other objects ofthe invention will become apparent hereinafter.

The novel nitro plastic propellants of the present invention aregenerally more satisfactory than any known solid propellant composition.They are, for example, substantially smokeless, by virtue of theirdesirable oxygen balance. Moreover, these propellants exhibit a veryhigh thrust potential due to their high specific impulse and the factthat substantially none of their potential energy is wasted inincomplete combustion to smoke. Likewise, since any effluent gases fromcombustion of these propellants are substantially non-corrosive andinnocuous, detcrioration of wiring and other equipment is avoided. Assubstantially all of the oxygen needed for complete combustion ispresent in the nitro plastic itself, the propellants do not depend uponatmospheric oxygen for their combustion and are therefore to bedistinguished from other propellants which are unlike in this respect.The temperature coefiicient of nitro plastic propellants, as indicatedin some of the examples, is usually a very desirable low number incontrast to the more undesirable higher coeflicients of previously knownpropellants. Other advantages accruing to the use of nitro plasticpropellants will be apparent to one familiar with the art, and, asimportant among these advantages may be mentioned the relative stabilityof the N0 groups which are characteristic of nitro plastics as comparedto the more unstable ONO groups present in many commonly employedexplosives or combustible materials.

Oxygen balance of the combustible nitro plastics of the presentinvention may be calculated readily. When it contains suflicient oxygento burn all the carbon to carbon dioxide and all the hydrogen to water,the compound is considered to be in perfect oxygen balance. It is thensaid that the compound has an oxygen balance of zero, the value beingdetermined by inserting the values in the formula:

A compound having a minimum oxygen balance of approximately 50 isconsiderable entirely suitable. This calculation is based on theassumption that a compound containing sutficient oxygen to burn all thecarbon to carbon monoxide and one-third of the hydrogen to water will beproductive of substantially no smoke. Likewise, it is considered that apropellant having a minimum oxygen balance of minus is suitable for allpractical purposes, and experimental tests with compounds having such aminimum oxygen balance of minus 80 have proved the 3 correctness of thisassumption. At any greater negative value, the smoke produced anddecreased thrust per weight of fuel makes use of the propellantundesirable.

Procedure for calculating burning-law exponents or temperaturecoefiicients is also known (Crawford and Huggett, O.S.R.D. Report 4009;see also O.S.R.D. Report 5577, p. 52). This procedure allows theindirect evaluation of the temperature coetiicient of a fuel by theexperimental measurement of burning-rate change with respect topressure. Assuming that the Paul Vielle equation proposed by the FrenchPhysicist in 1893, holds,

where: r is the linear burning rate of a powder, and n are constants fora certain composition, and P is gas pressure.

It follows that:

d log 1' d log P (rilogP 1 dlogr) dT p rlT K where T equals absolutetemperature and area of burning surface of propellant cross-sectionalarea of throat Experimental burning rate measurements in a Crawford bombcompare very favorably with actual combustion data obtained by the useof the propellant in midget motors. The compositions of the presentinvention generally exhibit very low temperature coeflicients.

The propellants of the present invention comprise a nitro plastic havinga specific oxygen balance. The requisites of such a nitro plastic may befurther elucidated as follows:

(a) nitro-: it must contain NO groups, in contrast to other groupssometimes called by the misnomer nitro which are not N0 groups.

(b) -plastic: it must be of high molecular weight, i.e., a polymer;soft, moldable, or pliable.

(c) It must have a minimum oxygen balance of minus 80, calculatedaccording to the equation given previously.

Such suitable nitro plastics may be of various types. These may be, forexample, as follows:

(a) Condensation products of nitro aldehydes, nitro acids, nitro acidchlorides, nitro alcohols, nitro aromatic chlorides, with preformedpolymers. Representative of this type of nitro plastics are thecondensation products of 2,3,3-trinitropropanol,2,4,6-trinitrobenzaldehyde, nitrofurfurals or poly-(2',2',2trinitroethyl) benzaldehydes with polyvinyl alcohol or polyvinylamine,such products being nitro acetals and nitro imides, respectively; thecondensation product of picryl chloride with polyvinylamine; thecondensation products of 2,4,6-trinitrobenzoyl chloride withpolyvinylamine, i.e., the polyvinyl amide of trinitrobenzoic acid; thecondensation product of phenylisocyanate and polyvinylamine afternitration to introduce N0 groups; and the like.

(b) Condenstaion products of nitro compounds, e.g., nitro prafiins, withpolyvinylaminc, such as the condensation products therewith ofdinitromethane, nitroform, 1,1- dinitroethane, tetranitroethane,hexanitroethane, 2,3,3-trinitropropanal, and the like.

(c) Polymers of diisocyanates and diamines, with subsequent nitration ofthe product where necessary. This class includes the nitration productsof m-phenylene diisocyanate, toluene diisocyanate, ethylene diisocyanateand 7 known.

(g) Polymers of 1,3-dichloro-2,4,6-trinitrobenzene with hydrazines, withfurther nitration where practical if desired. Representative hydrazinesare hydrazine itself and oxalyl dihydrazide.

(11) Polymers of 1,3-dichloro-2,4,6-trinitrobenzene with itself by theuse of a powdered copper polymerization agent.

(i) Polymers of polynitromethanes, formaldehyde, and ammonia through useof a Mannich-type reaction.

The nitration of polymers, where required, may be conducted according toconventional procedure. Thus, for example, nitration may be accomplishedwith fuming nitric acid or with mixed concentrated sulfuric andconcentrated nitric acid. Mild conditions are generally advisable topreclude disintegration of the formed polymer, and nitration of polymersalready containing highly nitrated groups is generally not advisable.

Procedure for preparing the compositions of group (a) above mayconveniently be such as known in the art and further elucidated by theexamples. The starting aldehydes and methods for their preparation arealready Trinitrobenzaldehyde has been prepared by Sachs and Evcrding,Berichte 35, 1236 (1902), ibid. 36, 999 (1903) and by Secareanu,Berichte 64, 836 (1931). 2,3,3-trinitropropanal dipotassium salt may beprepared from mucubromic acid (from bromine and furoic acid of furfural,Hill, A. Chem. Jour. 3,4 (1881)) according to the procedure of Torrey,Am. Chem. Jour. 24, 457 (1900). Nitrofurfural may be prepared by theprocedure of R. Marquis (Comp. rend. 132, -142 (1901); ibid. 134,776-777 (1902); Br. Chem. Ab. 80, I, 222 (1901); ibid. 82, I, 483 (1902)or Gilman and Wright, J. Am. Chem. Soc. 52, 2550-2554, 4165-4166 (1930).Aromatic nitro aldehydes may also be prepared by the oxidation ofcorresponding methylated hydrocarbon derivatives according to theprocedure of Thiele and Winter, Annalen 311, 353 (1900). The method ofOrganic Synthesis, Coll. vol. II, p. 442, is also applicable to thepreparation of nitro aldehydes in general. Methods for synthesis of thealcohols are known and in some cases the alcohols are commerciallyavailable. Polyvinylamine may be prepared as indicated by Reynolds andKenyon, J. Am. Chem. Soc. 69, 911 1947 The preparation of group (b)polymers is fully described in the examples, the starting material beingknown.

The preparation of group (a) polymers is also disclosed in the examples,the starting materials being known. Diisocyanates may be prepared fromhydrazides by the Curtius reaction (Curtius and Hechtenberg, J.

Praet. Chem. 105, 289-318 (1923)).

The remaining types of nitro plastics may be prepared according to themethod given in the examples, the starting materials being known.

While nitro plastics of prescribed oxygen balance are themselves suitedfor use as the propellant without. additaments, it may in some cases bedesirable to in clude in the propellant a combustible additament, suchas a plasticizer, filler, or the like. The nitro plastics may, forexample, be plasticized with compounds which are also in satisfactoryoxygen balance so that the plasticized product falls within theprescribed range. Compounds which may be incorporated with the nitroplastics,

as plasticizers or additives are o-nitrotoluene, 1,1,2,2-tetranitroethane, 2,2-dinitropro-panol acetate, nitromethane, nitroform,tetranitromethane, methyl nitroacetate, ethyl nitroacetate, glycoldinitrate, glyceryl trinitrate, mannitol hexanitrate,2,2,3,3-tetranitrobutane, 2,3,3-trinitroisopentane,2-methyl-2,3,3-trinitropentane, 2,3,3-trinitroisohexane, nitroguanidine,and the like. For optimum stability of the composition, it is consideredsomewhat less desirable to employ -ONO2 containing compounds thanto-employ --NO containing compounds, as the former. are usuallyrelatively unstable, although otherwise satisfactory.

Organic plasticizers or additives other than those mentioned above, suchas guanidine or urea derivatives, dibutyl phthalate, etc., may also beemployed, providing that the relative quantities of nitro plastic andplasticizer are chosen= for suitable compatibility and so that theplasticized composition is-stillin proper oxygen balance.

When the nitro plastics are plasticized with the above or similarplasticizers, determinations on the polymer indicate a very low burningrate exponent. This is very important as indicative of a low pressureand temperature sensitivity, which, as mentioned above, is highlydesirable in a solid propellant of the type here concerned.

Moreover, it has been found that, if desired, a minor proportion of asolid inorganic oxidizer such as ammonium nitrate, potassium nitrate,ammonium picrate, or potassium perchlorate may be incorporated into thenitro plastic and plasticization accomplished subsequently thereto. Whensuch procedure is followed, the composite plasticized nitro plastic andoxidizer composition still is of a very desirable nature, exhibiting aburning rate exponent only slightly higher than that of the plasticizedpolymer itself. By incorporation of such an inorganic oxidizer into thenitro plastic, it is possible to use as plasticizer compounds other thanthe nitro com pounds listed above, if desired, making up the lack ofoxygen balance in the composition through employment of a selectedinorganic oxidizer. It is, of course, to be understood that perchloratesand other corrosive or smoke-producing compounds are to be avoided foroptimum utility and smokelessness.

The following examples are illustrative only and are in no way to beconstrued as limiting.

EXAMPLE 1 Polyvinyl-Acetal of Trinitrobenzaldehyde (a) To a suspensionof 0.870 mole (70.4 grams) of high viscosity polyvinyl alcohol in 600milliliters of glacial acetic acid there was added one mole (241 grams)of 2,4,6-trinitrobenzaldehyde dissolved in 1000 milliliters of glacialacetic acid. An acid catalyst, consisting of 20 milliliters ofconcentrated hydrochloric acid diluted with twenty milliliters of water,was added with stirring and the reaction continued for 65 hours at atemperature of about 60 degrees centigrade. The transparent solution wasthen dropped into about ten gallons of water with vigorous stirring. Theprecipitated fibrous nitro acetal was filtered, washed with one percentsolution of sodium carbonate and then with water. The nitro acetal resinwas obtained in a yield of about 80 percent and found to be yellow incolor, combustible, and to have, a softening point of 85 degreescentigrade.

The polynitro acetal plasticized readily with tetranitromethane, methylnitroacetate, nitromethane, and onitrotoluene.

(b) One-tenth of a mole (24.1 grams) of 2,4,6-trinitrobenzaldehyde wasdissolved in 50 milliliters of glacial acetic acid (or other solvent).To milliliters of the same solvent there was added 7.0 grams ofpolyvinyl alcohol and stirring employed until the alcohol was dissolvedor dispersed. This represented a molar ratio of the aldehyde to thealcohol of 1.25, where a mole of polyvinyl alcohol is considered as Thetwo solutions were transferred to a 300-rnilliliter wide-mouth Florenceflask equipped with a stirrer and placed in a 55 degree centigradethermostat. After the desired amount of dilute hydrochloric acid (equalparts by volume of water and concentrated dilute hydrochloric acid) wasadded, the mixture was allowed to react with stirring for the desiredperiod of time (see table below).

t the end of the reaction time, the contents of the flask were addeddropwise to four liters of water with very vigorous agitation at roomtemperature. The plastic formed immediately and was separated from theaqueous solution by filtration. The product was washed with dilutesodium bicarbonate and then with water until the pink color due to theaction of sodium bicarbonate had disappeared. The white plastic mass wasfinally dried at 60 degrees centigrade. Conditions under which the Whilethe runs employing glacial acetic acid as solvent resulted in a clear,brown solution, complete solution of the reactants was not obtained inrun 3 where methanol was used as a solvent.

EXAMPLE 2 Polyvinyl A cetal of S-Nitrofurfural (a). To. a suspension of0.2 mole (17.6 grams) of high viscosity (45-55 centipoises) polyvinylalcohol in 200 milliliter of glacial acetic acid there was added 0.2mole (48.6 gram) of S-nitrofurfural diacetate and eight milliliters ofsix-N hydrochloric acid. The mixture was stirred mechanically for hoursat 60 degrees centigrade. The clear brown solution was then addeddropwise to about two gallons of water with vigorous stirring. Theprecipitate was washed with a two percent sodium carbonate solution andthen with water. The dried, white polymer burned readily in air and hada softening point of about degrees centigrade.

'(b) In a SOD-milliliter round-bottom three-neck flask equipped with astirrer was placed 200 milliliters of glacial acetic acid containing 0.2mole (48.6 grams) of S-nitrofural diacetate. After adding eightmilliliters of six-N hydrochloric acid and 0.2 mole of high Viscositypolyvinyl alcohol which had been emulsified in 150 milliliters ofglacial acetic acid, the contents of the flask were maintained at 57degrees centigrade for 23 hours. At the end of this time, the polyvinylalcohol had completely dissolved. The solution was added dropwise intoabout ten liters of water with vigorous stirring. The solid product,which immediately formed, consisted of small white balls. Theprecipitate was Washed with two percent sodium carbonate solution, thenwith water, and dried in an oven at 65 degrees centigrade. The driedproduct burned readily in air. The apparent density, determined bypouring a weighed quantity of the polymer into a graduated cylinder, was0.12. The product weighed 34 grams, representing about 81 percent of thetheoretical yield. The polymer did not liquefy under 200 degreescentigrade with slow rise in temperature.

The nitro acetal polymer plasticized readily with onitrotoluene ormethyl nitroacetate.

EXAMPLE 3 Polyvinyl Acetal of 2,3,3-Trinitropropanal Twenty grams of thedipotassium salt of 2,3,3-t1initropropanal was added slowly to 100milliliters of glacial acetic acid. A definite decrease in the acidityof the acid was noted upon addition. The mixture was placed in around-bottom three-neck flask fitted with a thermometer and a stirrerand 4.4 grams of polyvinyl alcohol suspended in 100 milliliters ofglacial acetic acid added thereto The solution was heated to 90 degreescentigrade and refluxed for 48 hours, whereupon the mixture becameviscous and was poured into cold water, washed and separated. The nitroacetal which was obtained in this manner burned with an almost smokelessflame, and plasticized or formed intimate admixtures withtetranitromethane, 2,2-dinitropropane and methyl nitroacetate.

EXAMPLE 4 Percent Nitroacetal 52.25 Ammonium nitrate 34.83 Methylnitroacetate 12.92

The strand was placed on a glass plate at room temperature (27 degreescentigrade) to determine weight increase (hygroscopicity) or weight loss(volatility of methyl nitroacetate) The weight of the sample and theuniform texture thereof did not change over a period of one month.

EXAMPLE 5 Forty grams of ball-milled polyvinyl acetal of2,4,6-trinitrobenzaldehyde and sixteen grams of dried ammonium nitrate(0.1 percent calcium phosphate added) were tumbled in the ball mill ofExample 4. After 24- hours of blending, the powdered mixture was mixedwith tetranitromethane (20.6 grams) of which 6.7 grams volatilizedInitial Peak Burning Pressure, Pressure, Rate,

p.s.l. p.s.l. Inches/ Second When graphed, the value of the slope n,using the method of least squares, was found to be 0.57, which is a verylow burning-law exponent.

EXAMPLE 6 Suflicient tetranitromethane is added to the desired quantityof pulverized nitro acetal to yield a mixture containing 28 percentthereof. If the mixing is done by hand with a steel spatula, about 40grams of the nitro acetal worked on a 10 x 10 inch glass plate isconvenient. This amount requires 16 grams of tetranitromethane, which isquickly absorbed by the plastic, and the mixture may be finally kneadedwith the fingers. A stifi, brown, doughy mass results, which is shapedby rolling on a plate to form strands of whatever length and diametermay be desired.

Burning rate determinations were conducted with strands of (a) polyvinylacetal of 2,4,6trinitrobenzaldehyde plasticized with 28 percenttetranitromethane and (b) 75 percent potassium perchlorate-25 percentpeptized rubber. The strands were coated with glyptal enamel beforedeterminations in a Crawford bomb. The results were as follows:

COMPOSITION (a) Initial Peak Burning Pressure, Pressure, Rate,

p.s.i. p.s.l. Inches] Second The burning-law exponent n for thiscomposition was 0.36, a very low value.

COMPOSITION (b) Initial Peak Burning Pressure, Pressure, Rate,

p.s.i. p.s.i. Inches/ Second The burning-law exponent for composition(b) was n=0.74.

H2O (NOz)a 20H20 NR3 plastics in the same manner arel,1,4,4-tetranitrobutane, 1,1,3,3 tetranitropropane, 1,3 dinitropropane,tetranitropentane and bis-beta,beta-dinitrodiethyl ether.

EZN

EXAMPLE 7 In a burning-rate experiment similar to that of Example 6, astrand of 72 percent polyvinyl acetal of 2,4,6-trinitrobenzaldehyde and28 percenttetranitromethanecomposition, coated with glyptal enamel,exhibited a burninglaw exponent of 0.32.

EXAMPLE 8 Conversion of Dinitromethane Into a Plastic 10 N02 ]-OH2NHCH2.

l lo: n

(a) Eleven and four-tenths grams of 37 percent formalin (0.141 moleformaldehyde) and 2.8 grams of 28 percent amrnonia-solution (0.047 moleof ammonia) were mixed together and placed in a three-neck flaskprovided with reflux condenser, stirrer, and thermometer. contents ofthe flask were cooled to five degrees centigrade and five grams ofdinitromethane (0.047 mole) dissolved in 6.6 grams of benzene addeddropwise. required about 30 minutes. 21 hours at room temperature (25degrees centigrade) and for an additional hour at about 50 degreescentigrade. The reaction mixture was then poured into water and anamorphous substance separated and dried in a vacuum desiccator. burnedreadily and plasticized with cellulose nitrate and methyl nitroacetate.

The

The addition The mixture was stirred for The product was a brown powderwhich (5) Five and two-tenths grams of 37 percent formalin solution(0.063 mole formaldehyde) and 1.4 grams of 28 percent ammonia solution(0.021 mole of ammonia) weremixed together and placed in aZOO-milliliter roundbottom three-neck flask provided with stirrer,thermometer, and reflux condenser. cooled down to 3 degrees centigradeand 2.3 grams (0.021 mole) of CH (N0 dissolved in 15 millilitersofbenzene added dropwise thereto. minutes, during which the temperaturerose from 3 degrees centigrade to +3 degrees centigrade. continued for48 hours while the reaction mixture was allowed to warm to roomtemperature (25 degrees centigrade). water to yield a plastic materialwhich could be pulverized to a brown powder after drying in a vacuumdesiccator over drierite.

The contents of the flask were 40 Additlon required ten Stirring was Thecontents of the flask were then diluted with Other polynitro compoundswhich may be converted to EXAMPLE 9 Condensation of m-PhenylenediamineWith Ethylene Bromide and Subsequent Nitration 6O NHz BICHtCHzBl OgN N02(a) A-solution of freshly rectified m-phenylenediamine 75.

(40.8 grams) in 30 milliliters of ethylene glycol was placed ina-250-rnilliliter three-neck flask equipped with thermometer, stirrer,and reflux condenser. Ethylene bromide (16.4 milliliters) was added froma burette, and the mixture slowly heated. When the temperature reacheddegrees centigrade, a vigorous exothermicv reaction occurred and thetemperature rose rapidly to 150 degrees centigrade. After this firstreaction had subsided, the resulting dark red solution was refluxed at190 degrees centigrade for minutes. The viscous reaction mixture at 150degrees centigrade was poured into 1750 milliliters of cold water, andthe aqueous mixture neutralized with dilute sodium hydroxide solution. Adark red plastic material precipitated as a ball, was removed, washedthoroughly with hot water, and dried in an oven at 110 degreescentigrade. The dried material was cooled and pulverized, yielding 31.3grams of an orange powder.

For nitration of this material, 100 milliliters of fuming nitric acid(specific gravity 1.5) Was cooled'to zero degrees centigrade and 0.1gram of urea added. Eight gramsof the orange powder was then added inapproximately 01 gram portions, while holding the temperature below fivedegrees centigrade. The addition required one hour, whereafter theresulting brown solution was allowed to-warm to 20-degrees centigrade,andwas then heated to 40 degrees centigrade for 15 minutes. The solution was cooled to roomtemperature and poured into one liter ofdistilled water. A tan precipitate formed and was filtered off, washedwith water, dilute Na CO solution and then more water,. and finallydried. A yield of 12.04 grams of tan powder containing 20.55 percentnitrogen -was obtained. This material burned well, leaving only someresidue. Therefore 10.0 grams were added slowly to 100 milliliters offuming nitric acid at 20 degrees centigrade, and the resulting solutionheated for fifteen minutes at 92 degrees centigrade. Vigorous evolutionof N0 occurred. The reaction mixture was then cooled to 20 degreescentigrade and poured into one liter of water. The yellow precipitatewhich formed was fil tered off, washed with Na CO solution, water, anddried on the filter. A yield of 8.3 grams of tan powder containing 20.00percent nitrogen was obtained. The burning. properties of this materialwere somewhat better than those of the once nitrated material.

([2) A solution of 31.0 grams of freshly rectified m-phenylenediamine in30 milliliters of dioxan was placed in a 250-milliliter three-neck flaskequipped with thermometer, stirrer, and reflux condenser.v Ethylenebromide (12.42 milliliters) was added from a burette, and the solutionslowly heated. An exothermic reaction began at 65 degrees centigrade,the temperature rising rapidly to 110 degrees Centigrade. At thispoint'a gummy mass precipitated from solution. This mixture was refluxedfor one hour and then poured into one liter of water. The resultingslurry was neutralized and the greenishyellow plastic which separatedremoved as a ball. This was washed thoroughly with several portions ofNa CO solution followed by several portions of water. The washed productwas dried in a vacuum desiccator and a yield of 16.73 grams ofgreenish-yellow powder containing 16.12 percent nitrogen obtained. Thismaterial softened at -135 degrees centigrade. The starting materials canalso be condensed in nitromethane or without a solvent.

For nitration, 10.0 grams of this material were added in approximately0.1 gram portions to milliliters of fuming nitric acid cooled to zerodegrees centigrade. The brown solution which resulted was allowed towarm to 20 degrees Centigrade, stand for one hour, and then poured intoone liter of distilled water. The brown solid which precipitated wasfiltered 01f, washed and dried. A yield of 13t25 grams of tan powdercontaining 19.95 percent nitrogen was obtained. This material burnedvery vigorously and could be plasticized with methyl nitroacetate.

1 1 EXAMPLE 10 Condensation of m-Phenylenea'iamine With TrimethyleneBromide and Subsequent Nitration H N NH: BrCHzCHzCHzBr NO: N N02 OzN N01The procedure described in Example 9 was repeated using 26.5 grams ofm-phenylenediamine, 12.50 milliliters of trimethylene bromide and 30milliliters of dioxan. A yield of 17.0 grams of greenish-yellow powdercontaining 15.92 percent nitrogen was obtained.

Nitration of the product according to the procedure of Example 9 gives aplasticizable resin which burns very well.

EXAMPLE 11 Condensation of Ethylene Diisocyanate With Ethylene Diamineand Subsequent Nitration 0=C=NCH2CH2N=C=O+HgNCH2CHzNHI v [-CHCHzNHCONH-]n+HNOa N02 N 02 --CH2GH2NC ON 111 A solution of 1.12 grams(0.01 mole) of ethylene diisocyanate in milliliters of dioxan was addeddropwise to a solution of 0.60 gram (0.01 mole) of ethylene diamine in10 milliliters of dioxan. A white precipitate formed immediately and wasfiltered oil. The yield was 1.4 grams.

Nitration of this product was eifected by adding 1.0 gram of thematerial in small portions to 10 milliliters of fuming nitric acid atroom temperature. The resulting solution was poured into cold water, togive the white nitrated product, which burned well.

EXAMPLE 12 Condensation of m-Phenylenediamine With Phosgene andSubsequent Nitration HnN NHz NO: IITO: N01

Oz N02 A solution of 10.8 grams (0.10 mole) of purifiedmphenylenediamine in 50 milliliters of chloroform was placed in a largetest tube and 9.9 grams (0.10 mole) of phosgene bubbled in over a periodof 30 minutes. A black tacky material precipitated, and on furthertreatment the precipitate turned to a white powder. This material wasfiltered 01f, washed with chloroform, and dried, yielding 13.9 grams ofwhite powder.

Five grams of this material was added in small portions to 25milliliters of fuming nitric acid at zero degrees centigrade. A deepbrown solution formed, and was allowed to stand for ten minutes. Thissolution was added 12 to 500 milliliters of cold water, whereupon a tanprecipitate formed. This was filtered off and dried, yielding 5.7 gramsof material which burned vigorously and was plasticized with methylnitroacetate.

EXAMPLE 13 Condensation of m-Phenylenediamine With Ethylene Diisocyanateand Subsequent Nilration HzN NHg+0=C=NCHzCHz-N=C=O 11 NO; $01 N02 N02N01 -N-O O-N-CHzCHzNC ON- On N0 A solution of 1.55 grams of ethylenediisocyanate in 10 milliliters of o-dichlorobenzene was added dropwiseto a hot solution of 1.5 grams of m-phenylenediamine in 10 millilitersof o-dichlorobenzene. A gummy white product precipitated and hardened oncooling. This was filtered oh? and dried, yielding 2.8 grams of product.

This product (2.0 grams) was nitrated by addition in small portions to20 milliliters of fuming nitric acid at room temperature. The resultingsolution was heated to 70 degrees centigrade for 15 minutes, thencooled, and poured into water. A tan material precipitated, was filteredoff and dried. This material burned fairly well, leaving only a smallamount of residue.

Renitration under similar conditions, but with hot mixed acidsapparently did not improve the burning qualities by any appreciableamount.

EXAMPLE 14 Condensation of m-Phenylenediamine With Ethylene Oxide,Polymerization, and Subsequent Nitration an NHz-CHzCHzOH H250 N01 N01NO:

OzN N02 (a) Liquid ethylene oxide (18.6 grams) was poured into asolution of 45.6 grams of freshly distilled m-phenylenediamine in 200milliliters of methanol, and the resulting mixture was rectified atreduced pressure, and the following fractions collected:

(1) Bl. 30 at 150 mm.l ml.--methanol (2) B.P. 127-185 at 2.5mm.-m-phenylenediamine (3) BF. 188 at 3.5 mm.21.6 g. Fraction 3solidified on standing, and recrystallization from chloroform gave Whitecrystals melting at 62-63 degrees centigrade and containing 18.65percent nitrogen. (18.42 calculated forN-(fi-hydroxyethyl)-mphenylenediamine.)

(b) A solution of 74.7 grams of freshly rectified m- (2) HP. 191 at 3rnm.-1.0 g.

phenylenediamine in 250 milliliters of water was heated to boiling, and20.4 grams of ethylene oxide was bubbled through the solution. Theeffluent gas was passed through a water-cooled reflux condenser and intoa Dry-Ice trap. When all of the ethylene oxide had been added, thecontents of the Dry-Ice trap were allowed to vaporize and pass throughthe solution.

The resulting solution Was then rectified at reduced pressure, and,after the water had been removed, the following fractions werecollected:

The resulting solution was then rectified at reduced pressure, and,after the water had been removed, the following fractions werecollected:

(1) HP. 130-133" at 3 mm.--38.0 g.-m-phenylenediamine 3 B.P. 192494 at 3mm.28.6.-M.P. 61-62 0.

Fraction 3 was the desired N-(B-hydroxyethyD-mphenylenediamine.

(c) Five grams of molten N-(fi-hydroxyethyl)-m-phenylenediamine wasadded to 25 milliliters of concentrated sulfuric acid, and the mixturecarefully warmed until solution was complete. The resulting clear,colorless solution was cooled to five degrees centigrade andconcentrated nitric acid (20 milliliters) added dropwise thereto at 5-10degrees centigrade. The solution turned to a deep brown color, but nofumes were evolved. The solution Was allowed to warm up to 40 degreescentigrade and was held at this temperature with cooling until reactionceased. The mixture was then poured over crushed ice, and the resultingslurry boiled to coagulate the solid product into a plastic ball. Thiswas washed thoroughly with hot water and dried in a desiccator to yielda reddish-brown material which burned with extreme vigor. This materialmelted at 6070 degrees centigrated with some decomposition.

EXAMPLE 15 Condensation of m-Phenylenediamine with Ethylene Oxide andSubsequent Nitration HQN NH; 0112-0112 O N N02 A solution of 169.8 gramsof freshly rectified rn-phenylenediamine in 500 milliliters of methanolwas placed in a one-liter flask equipped with a vapor inlet tube, athermometer, and a Dry Ice-cooled reflux condenser. The solution wascooled to five degrees Centigrade and 72.5 grams of ethylene oxidebubbled in over a period of three hours. An exothermic reactionoccurred, and the solution turned blue. This solution was allowed towarm to room temperature and stand for two hours, whereafter themethanol was removed by distillation under reduced pressure. A viscousred residue, weighing 219 grams, remained in the flask.

Fuming nitric acid (100 milliliters) was cooled to zero degreescentigrade in a 250-milliliter three-neck flask and 15.6 grams ofviscous reaction product added dropwise over a period of four hours at0-5 degrees Centigrade. The dark red resulting solution was allowed towarm up to 20 degrees centigrade and stand for one hour, and was thenadded dropwise to 1100 milliliters of percent acetic acid. A tanmaterial precipitated, was filtered off, and placed in 200 millilitersof hot water. A

EXAMPLE 16 (CrHsO CO-NHCHzCHzNHhCO 2 C (I. A

Hm ONH A HzN-NH: 2 I

("l-NH O (e) Condensation of N,N'-his-(beta-arninoethyl)-urea withdiisocyanate.

(f) Subsequent nitration.

(a) Reaction of Ethylene Diamine With Diethyl Carbonate Ethylene diamine(92 grams, 1.53 mole) was heated to reflux temperature in a250-milliliter, three-neck flask equipped with a stirrer, refluxcondenser, and dropping funnel. Diethyl carbonate (60 grams, 0.5 mole)was added dropwise over a period of six hours, and the resultingsolution was refluxed for an additional 18 hours. The solution was thentransferred to a distilling flask and two fractions distilled at reducedpressure. The first fraction, boiling below 146 degrees centigrade at 35millimeters of mercury pressure consisted of ethanol, unreacted ethylenediamine, and diethyl carbonate. The second fraction, boiling at 146-161degrees centigrade at 35 millimeters of mercury pressure was rectifiedunder reduced pressure, and 33.4 grams of material boiling at 1065-1072degrees Centigrade at 4 millimeters of mercury pressure obtained. Thiswas the monourethan of ethylene diamine. The residue from thedistillation solidified on cooling, and recrystallization of a portionof this material showed it to be the diurethan of ethylene diamine, MP.112-113 degrees Centigrade.

(17) Reaction 0 the Monourethan of Ethylene Diamine With Phosgene Asolution of 6.6 grams of the monourethan of ethylene diamine in aqueouspotassium hydroxide (20 milliliters H O+2.8 grams of KOH) was placed ina small flask and 2.5 grams of phosgene bubbled into the solution. Anexothermic reaction occurred, and, when the solution was cooled, a whitecrystalline material precipitated. This was filtered off andrecrystallized from water, giving 2.65 grams of a white crystallinesolid melting at 166-168 degrees centigrade. A nitrogen analysis showed19.64 percent nitrogen in the compound, as compared to a theoreticalvalue of 19.3 percent for N,l l'-bis-(beta-carbethoxyamino ethyl) -urea.

15 (c) Reaction of N,N-Bis-(Beta-Curbetlzoxyamin'oethyl)- Urea WithPhthalie Anhydride A mixture of 1.45 grams (0.05 mole) of the diurethanfrom (b) and 1.49 grams (0.10 mole) of phthalic anhydride was heated ina test tube until gas evolution from the molten mass ceased. The meltwas then cooled and dissolved in boiling ethanol. When this solution wascooled, 1.8 grams of white crystals melting at 155-156 degreescentigrade precipitated. This material was N,N-bis-(beta-phthalimidoethyl)-urea.

(d) Reaction of N,N'-Bis-(Beta-Phthalimidoethyl)-Urea With HydrazineHydrate To a solution of 0.52 gram of 85 percent hydrazine hydrate in 10milliliters of ethanol was added 1.8 grams ofN,N'-bis-(beta-phthalimidoethyl)-urea. The resulting solution was heateduntil a white, gelatinous precipitate formed. Hydrochloric acid (2.6milliliters) was then added and the mixture filtered to remove phthalylhydrazide. The filtrate was concentrated to remove ethanol, and theresulting aqueous solution was neutralized with aqueous potassiumhydroxide. The solution was then saturated with potassium carbonate tosalt out the free amine which was taken up with ether. The ethersolution was dried over solid KOH, and then saturated with anhydrous HClto precipitate 0.27 gram of a white crystalline substance melting at113-115 degrees centigrade. This material is the dihydrochloride ofN,N'-bis-(betaaminoethyl) -urea.

(e and f) Condensation of the N,N'-bis-(beta-aminoethyl)-urea withdiisocyanates, e.g., m-phenylenediisocyanate, ethylene diisocyanate, andsubsequent nitration according to the procedure of the precedingexamples gives nitro plastics having very desirable burningcharacteristics.

Copper N02 O N NO; OzN N02 (a) A solution of 7.05 grams (0.025 mole) of1,3-dichloro-2,4,6-trinitrobenzene [Sudborough and Picton, J. Chem. Soc.89, 591 (1906)] in 75 milliliters of nitrobenzene was heated to boiling,and 17.5 grams (0.27 mole) of copper powder added in small portions tothe refluxing solution. The resulting brown suspension was refluxed forone hour; then cooled and poured into 500 milliliters of ether. Theresulting slurry was filtered and the filter cake extractedsuccessively, with ether, dilute hydrochloric acid, dilute nitric acid,and water. The remaining solid was dried to yield 4.5 grams of brownpowder. This material burned readily leaving little residue. The productwas chlorine-free and could be plasticized with methyl nitroacetate.

(b) A second experiment was carried out in the same manner as above, butthe solution was refluxed for sixteen hours instead of one hour. A yieldof 3.5 grams of chlorine-free product was obtained.

EXAMPLE 18 Reaction of 1,3-DichZora-2,4,6-Trinitrobenzene With EthyleneGlycol Cl Cl +110 CHzCHzOH O: N01

0 CH2CH2O- OgN NO:

To 25 milliliters of pyridine was added 1.0 gram ofl,3-dichloro-2,4,6-trinitrobenzene, whereupon a dark brown solutioncontaining a reddish brown precipitate was formed. The mixture washeated to reflux temperature, five drops of ethylene glycol added, and,after refluxing for six hours, cooled to zero degrees centigrade andfiltered. A small amount of tan crystalline material which did not meltbelow 250 degrees centigrade and which exploded when heated in an openflame was obtained. This material gave a negative Beilstein test forhalogen. The filtrate was poured over approximately grams of ice andacidified with concentrated HCl, forming a brown amorphous precipitate.This material was filtered off, dried, and found not to melt below 250degrees centigrade; to burn rapidly when ignited leaving little residue;and to give a positive Beilstein test for halogen. It apparently was notreadily plasticized with tetranitromethane or dibutyl phthalate.

EXAMPLE 19 Reaction of 1,3-Dichl0ro-2,4,6-Trinitrobenzene With HydrazineN0, No,

01 or -NIINH HzN-NH: OzN N O, OgN N 0:

(a) Five moles of hydrazine per mole of dichlorotrinitrobenzene.

A solution of 7.05 grams (0.025 mole) of 1,3-dichloro-2,4,6-trinitrobenzene in 300 milliliters of methanol was prepared and 40milliliters of absolute ethyl alcohol containing 0.10 gram of hydrazineper milliliter (0.125 mole total) added dropwise thereto with vigorousstirring. The addition required three hours, during which time thetemperature rose from 20 degrees centigrade to 33 degrees centigrade. The resulting slurry was stirred for 48 hours and then filtered, yieldinga black solid and black filtrate. The solid was washed free of hydrazinehydrochloride, and 2.2 grams of chlorine-free material melting at 175-95 degrees centigrade obtained. This product burned vigorously.

The filtrate was added to water and the resulting emulsion broken byaddition of sodium chloride. The solid was filtered off, and 1.3 gramsof brown solid, melting at 77-95 degrees centigrade, obtained. Thismaterial plasticized with methyl nitroacetate and was chlorine-free.

(b) Three moles hydrazine per mole of dichlorotrinitrobenzene.

A solution of 7.05 grams (0.025 mole) of dichlorotrinitrobenze-ne in 300milliliters of methanol was prepared and 24 milliliters (0.075 mole) ofthe alcoholic hydrazine solution added dropwise with stirring andcooling. The addition was carried out at 18-20 degrees centigrade over aperiod of two and one-half hours, the resulting solution being stirredfor 48 hours.

The solution was added dropwise in a steam distillation apparatus to oneliter of boiling water through which steam was being passed. Methanolwas stripped 011?, and an aqueous slurry of brown powder which remainedin the distillation flask filtered to give 3.0 grams of brown powder.This material could be plasticized with methyl nitroacetate.

(c) A solution of 7.05 grams (0.025 mole) of 1,3-dichloro-2,4,6-trinitrobenzene in 75 milliliters of ethanol wasprepared, and a solution of 2.94 grams (0.050 mole) of 85 percenthydrazine hydrate in 24 milliliters of ethanol added dropwise theretowith stirring. The mixture was stirred for hours at room temperature andfiltered to yield a brown precipitate and a black filtrate.

The precipitate was washed free of hydrazine hydrochloride withsuccessive portions of distilled water and yielded 3.2 grams of brownpowder melting at 108-115 degrees centigrade. This material burnedvigorously and could be plasticized with methyl nitroacetate.

tered ofi and dried, yielding 2.7 grams of a black solid' which meltedat approximately 60 degrees centigrade.

(d) This experiment was similar to (c) except that 5.88 grams (0.10mole) of hydrazine hydrate and 7.05 grams (0.025 mole) of1,3-dichloro-2,4,6-trinitrobenzene were used. When the reaction mixturewasfiltered after 122 hours, a brown filter cake and black filtrate wereobtained. The filter cake was washed free of hydrazine hydrochloride andextracted with benzene. The brown powder (3.3 grams) which was obtainedburned with extreme vigor and could be plasticized with the product fromthe reaction of potassium nitroform and acrylonitrile. When the filtratewas added to water containing Na SO a black gummy precipitate wasobtained which burned well.

(e) Experiment was repeated at a temperature of 40 degrees centigradeinstead of room temperature. The solid product obtained by filtrationweighed 3.86 grams. This was washed free of hydrazine hydrochloride andextracted with benzene to yield a reddish brown powder which could beplasticized with methyl nitroacetate.

(f) A solution of 5.5 grams of hydrazine sulfate in aqueous ethanol wasprepared and added rapidly with stirring and cooling to a solution of10.0 grams of 1,3-dichloro-2,4,6-trinitrobenzene in 90 milliliters ofdioxan. The resulting deep red solution was stirred for two hours atroom temperature, filtered to remove potassium sulfate, and addeddropwise to one liter of water. The stable emulsion which formed wasbroken by addition of sodium chloride. A dark brown solid precipitatedand was tiltered oflf and dried to yield 7.5 grams of a material whichmelted at 53-83 degrees centigrade. This product burned vigorously,contained some chlorine, and could be plasticized with methylnitroacetate to give a firm, semi-elastic product.

In an attempt to form a higher polymer, 6.0 grams of this material wasdissolved in 25 milliliters of dioxan and one milliliter of 85 percenthydrazine hydrate solution added thereto. A vigorous reaction ensued,whereafter the solution was heated for 48 hours to 85 degreescentigrade. The products isolated from the reaction mixture containedless chlorine, but did not seem to be much higher polymers as indicatedby the product obtained on plasticization with methyl nitroacetate.

(g) A solution of 10.0 grams of 1,3-dichloro-2,4,6-trinitrobenzene in100 milliliters of dioxan was prepared and a solution of 2.1 grams of 85percent hydrazine hydrate in 20 milliliters ofdioxan added dropwisethereto with vigorous stirring. A white precipitate and a small amountof black tar was formed. The mixture was transferred to a flask equippedwith a reflux condenser, heated at 85 degrees centigrade for 48 hours,cooled to room temperature, filtered to remove hydrazinedihydrochloride, and added dropwise to ice-water. The black tarryproduct was dried in a vacuum desiccator to yield a black, pitchlikesubstance melting at approximately 60 degrees centigrade.

(h) A solution of 2.94 grams (0.05 mole) of hydrazine hydrate in 20milliliters of glacial acetic acid was added to a solution of 14.1 grams(0.05 mole) of 1,3-dichloro-2,4,6-trinitrobenzene and 7.7 grams (0.10mole) of ammonium acetate in 100 milliliters of glacial acetic acid. Theresulting red solution was heated for 65 hours at 70-80 degreescentigrade. On cooling and filtering, 3.4 grams of ammonium chloride wasobtained. The filtrate was added dropwise to water, whereupon 2.0 gramsof brown powder precipitated. This material contained some chlorine,burned readily, and could be plasticized with methyl nitroacetate toyield a plastic-like material of low tensile strength.

(i) A solution of 5.88 grams (0.10 mole) of 85 percent hydrazine hydratein 20 milliliters of glacial acetic acid was added to a solution of 14.1grams (0.05 mole) of 1,3-dichloro-2,4,6-trinitrobenzene in 100milliliters of glacial acetic acid, and the resulting mixture heated for65 hours at 70-75 degrees Centigrade. It was then cooled, filtered, and1.8 grams of impure hydrazine dihydrochloride separated therefrom. Thefiltrate was added dropwise to ice water, whereupon 9.0 grams of ared-brown powder precipitated. This material contained chlorine, meltedat 105160 degrees centigrade, burned vigorously and plasticized readilywith methyl nitroacetate to give a firm material with low tensilestrength.

(j) To 13.7 grams of hydrazine sulfate suspended in 50 milliliters ofhot water was added 3.5 grams of po tassium acetate. The mixture wasboiled for five minutes, cooled to 70 degrees centigrade, diluted with30 milliliters of ethanol, and filtered to remove potassium sulfate. Thefilter cake was washed with 30 milliliters of hot ethanol, and thecombined filtrate and wash solution set aside for use in the reactionwith 1,3-dichloro-2,4,6-trinitrobenzene.

In a 500-milliliter three-neck flask equipped with reflux condenser andstirrer was placed 12.3 grams of 1,3-dichloro-2,4,6-trinitrobenzene and100 milliliters of ethanol. The mixture was heated to boiling and thepreviously prepared hydrazine solution added dropwise thereto. Theresulting black solution was refluxed for 16 hours, cooled, and filteredto give 11.5 grams of a black powder. After washing with hot water toremove potassium salts, 10.0 grams of potassium-free black powder wasobtained. This material burned rapidly leaving a moderate amount ofresidue, did not contain chlorine, and did not melt below 275 degreescentigrade. On heating to 375 degrees centigrade, slow decomposition wasobserved but there was no evidence of melting. It was insoluble inwater, acetone, alcohol and pyridine, and slightly soluble in benzene.With pyridine the product gave a tacky material which changed back topowder when the pyridine was evaporated.

(k) A hot solution of 8.8 grams (0.15 mole) of percent hydrazine hydratein 25 milliliters of glacial acetic acid was added rapidly to arefluxing solution of 14.1 grams (0.05 mole) of1,3-dichloro-2,4,6-trinitrobenzene in 25 milliliters of glacial aceticacid. The mixture was deep red in color. The temperature was thenlowered to degrees centigrade, the mixture stirred for 24 hours, and theresulting black suspension added to 750 milliliters of water. A brownprecipitate was formed, filtered off and dried, yielding 5.4 grams of abrown powder which burned readily and could be plasticized with methylnitroacetate.

EXAMPLE 20 Condensation of 1,3-DichZora-2,4,6-Trinitrobenzene WithOxalyl Dihydrazide Preparation of oxalyl dihydrazide, (CONHNH accordingto Schoefer and Schwan (J. Prakt. Chem. 51, 194). Yield: 85 percent oftheory.

(a) A solution of 7.05 grams of 1,3-dich1oro-2,4,6-trinitrobenzene in 50milliliters of hot ethylene glycol was added slowly to a boilingsolution of 2.70 grams of oxalyl dihydrazide in 50 milliliters ofethylene glycol. The mixture turned deep red in color and was refluxedfor two hours, cooled to room temperature, and added dropwise to oneliter of water. A brown solid precipitated and was filtered off. Dryingat 55 degrees centigrade resulted 19 in a black pitch-like substancewhich, when dry, weighed 29 grams.

(b) A mixture of 7.05 grams of 1,3-dichloro-2,4,6- trinitrobenzene, 2.80grams of oxalyl dihydrazide, and 12 milliliters of ethylene glycol wasplaced in a twelve-inch Pyrex test tube equipped with stirrer,thermometer, and gas inlet and outlet tubes for operation under nitrogenatmosphere. The tube was heated slowly while nitrogen circulated throughthe system. At 80 degrees centigrade an exothermic reaction began, andthe mixture turned to a viscous orange mass. When this reaction hadsubsided, the temperature was slowly raised to 127 degrees centigrade,where a second more vigorous reaction started. The mass became darkbrown in color, HCl was evolved, and the temperature rose to 150 degreescentigrade. This temperature was maintained for one hour by applyingheat as the reaction became less vigorous, whereafter the hot fluidmixture was poured into one liter of cold water. Five grams of ared-brown powder precipitated, was filtered olf, and was dried for 36hours in a vacuum desiccator. This product melted at 80-110 degreescentigrade, was readily plasticized with methyl nitroacetate, and burnedwell.

(c) This experiment was conducted in the same manner as (b), exceptthat, after heating for one hourat 134 degrees centigrade, a vacuum of70-80 millimeters of mercury was applied to the system and heatingcontinued for four hours at 110-120 degrees centigrade. The product (4.0grams) was a brown powder which melted at 135-65 degrees centigrade,plasticized readily with methyl nitroacetate, and burned well.

(a) Five-tenths gram of solid polyvinylamine was added to approximatelytwo grams of nitroform dissolved in ether. A yellow gummy precipitatewas formed which, upon drying, burned vigorously and left no ash.

(b) Twenty-seven milliliters of methanol containing .6 gram ofpolyvinylamine was placed in a 400-milliliter beaker and the solutioncooled to between zero and five degrees centigrade. Thirty-fivemilliliters of ether containing 2.20 grams of nitroform was added tothis solution with stirring. A yellow precipitate was formedimmediately. The mixture was stirred for one hour, methanol decantedoff, and the residue washed with methanol and dried in a vacuumdesiccator. The product burned very well.

(c) Approximately one gram of nitroform dissolved in ether was placed ina beaker and approximately three grams of polyvinylamine dissolved inalcohol added dropwise thereto. A yellow precipitate was formed. Thiswas rubber-like when wet but burned well after drying. (d) Six-tenthsgram of polyvinylamine was added to approximately two grams ofnitroform. The solution was shaken vigorously and allowed to stand atroom temperature for several days. A yellow gummy precipitate wasobtained which burned well on drying and analyzed for 24.4 percentnitrogen as compared to 35.5 percent calculated.

(e) One hundred milliliters of alcohol containing .5 gram of sodiumhydroxide Was placed in a 500-milliliter round-bottom three-neck flaskand one gram of polyvinylamine hydrochloride added in a nitrogenatmosphere. The solution was heated to 40 degrees centigrade and 1.8grams of nitroform dissolved in 50 milliliters of alcohol added dropwisewith stirring. Stirring and heating were continued for three hours,whereafter the yellow precipitate which formed was isolated, washed withwater, and dried in a vacuum desiccator.

(f) Polyvinylamine hydrochloride (.5 gram) was dis- 20 solved in waterand added dropwise to a water solution of potassium nitroform (2 grams)which was placed in a three-neck round-bottom flask equipped with astirrer. The yellow precipitate which was formed burned very well upondrying leaving very little ash. The mole ratio of polyvinylaminehydrochloride and potassium nitroform was 1 to 2.

(g) An experiment similar to (f) was carried out but with 1 to 3 ratio.The product burned well, leaving very little ash.

(11) An experiment similar to (1) was carried out but with 1 to 4 moleratio. The product burned about the same.

(1) One gram of polyvinylamine hydrochloride was placed in 250milliliters of freshly distilled ethanol contained in a separatoryfunnel. Nitrogen was bubbled through the alcohol solution and 0.5 gramof solid sodium hydroxide added. The solution was agitated for eighthours while nitrogen was introduced into the solution, after which thenitrogen inlet tube was lifted to just above the surface of the alcoholsolution. The NaCl formed was allowed to settle out and the alcoholsolution was syphoned over to a sintered glass disc funnel which wasconnected to a ground glass three-neck round-bottom flask equipped withstirrer, dropping funnel, and two two-way stopcocks. for a nitrogeninlet and a vacuum connection. The purpose of the filter was to removeany traces of NaCl remaining in the solution. After the solution hadfiltered through, the stirrer was started and 3.72 grams of nitroformdissolved in milliliters of ether added dropwise. A yellow precipitatewas formed immediately. The solution was stirred for six hours and thegummy precipitate was removed along with the mother liquor to around-bottom flask. The flask was stoppered and allowed to stand forseveral days with frequent shaking. The precipitate was then removed anddried in a vacuum desiccator. It burned very well.

(i) Identical with (i). Used 11.6 grams of HC(NO to one gram ofpolyvinylamine (3 to 1 ratio). The reaction time was 15 hours. Agreenish precipitate was obtained which burned well.

(k) Identical with (i). Used four grams of solid HC(NO of the highestpurity to 0.5 grams of polyvinylamine (2 to 1 ratio). The reaction timewas ten hours. A yellow brown product was obtained which burned well.

'(I) In this experiment freshly distilled water was used as solvent.Sodium nitroform was used in place of nitroform and polyvinylaminehydrochloride was used instead of polyvinylamine. The reaction time was16 hours and the ratio was 2 to 1. A greenish precipitate was obtainedwhich burned well.

EXAMPLE 22 Preparation of Polyvinylimide From Polyvinyl-Amine and2,3,3-Trinitr0propanal Polyvinylamine hydrochloride was preparedaccording to procedure of D. D. Reynolds and W. C. Kenyon, J. Am. Chem.Soc. 69, 911 (1947).

| NO: NO: NH: 11

,to in small amounts. An orange-yellow precipitate formed immediately.The reaction was continued for one-half hour, the mixture filtered, andthe residue washed with copious amounts of water, 10 percent aceticacid, and

again with. water. The, reactionproduct was. dried in a Thepolynitroimide' vacuum desiccator for. 24 hours; burned rapidly withvery little smoke, analyzed 19,88 per cent nitrogen, as comparedto.23.?, percent calculated, and appeared to be stableat a temperatureof 65 degrees c'entigrade.

(b) Ten grams of the dipotassinm salt of 2,3,3-trinitropropanal wasdissolved in" ammonia and one gram of polyvinylamine hydrochloridedissolved in water added dropwise thereto. The solution was allowed tostand overnight at room temperature. The ammonia solution wasneutralized, by dropping into a dilute HCl solution, whereupon a' yellowprecipitate wasobtained. The prodnot turned brown, upon drying andburned well.

Threeand three-tenths grams of the dipotassium salt of2,3,3-trinitropropanal was dissolved in Water and placed in around-bottom three-neck flask equipped with a stirrer and a droppingfunnel. Five-tenths gram of polyvinylamine hydrochloride was dissolvedin water and added dropwise to the solution of the dipotassium salt.Ayellow precipitate Was formed immediately. The product burned wellleaving some ash. The mole ratio ihthis experiment was one mole ofpolyvinylamine hydrochloride to two moles of the, dipotassium salt.

(d) Experiment similar to (0), only a one to three mole ratio was used.The product burned about the same as that obtained from (c).

(e) Experiment similar, to (c), only a one to four mole ratio was used.The product burned about the same as that obtained from (c).

The product obtained from the experiment using a one to two mole ratioshowed the highest percentage of nitrogen (Found 20.22 percent; 20.42percent N; calculated 23.30 percent N).

EXAMPLE 23 Preparation of Poly-N-Vinyl-Nitrobenzamide Q E (a) Threegrams of polyvinylamine was dissolved in water in a 300-milliliterround-bottom flask equipped with stirrer and dropping funnel, and tengrams of benzoyl chloride added dropwise thereto. A white precipitate'formed, was washed with water, and dried. The precipitatedpoly-N-vinyl-benzamide was then redissolved in methanol, reprecipitatedwith water, and finally dried at 70 degrees centigrade.

(b) Five-tenths gram of the polyvinyl benzamide from (a).was added inSmall amounts to 40 milliliters of fuming HNO at room temperature. Thesolution was allowed to stand for two hours and was then heated on asteam cone (60 degrees centigrade) for two hours. The nitration solutionwas poured into cold water with stirring to give a White precipitatewhich burned well. (c) Two grams of polyvinyl benzamide from (a) wasadded to 80 milliliters of mixed acid (85 percent concenrated H 80 15percent HNOg), and the soluti'onheated for six hours at 85-90 degreesCentigrade. The mixture was then filtered, cooled, and poured intoice-water. The yellow precipitate which was obtained analyzed for 13.08percent N as compared to 25.90 percent calculated.

Five-tenths gram of polyvinylamine hydrochloride was dissolved infreshly-distilledWater contained in a roundbottom three-neck flaskequipped with a stirrer and nitrogen inlet. To this solution Was added3.3 gram of the dipotassium' salt of 2,3,3-trinitropropanal in smallamounts. A strean i of nitrogen was passed through the solution for fourhours, whereafter stirring Was stopped and the solution filtered. Ayellow precipitate was obtained, washed, with water, 10 percent aceticacid and. It burned very well after drying in a;

again with water. vacuum desiccator.

EXAMPLEZS Condensation of Polyvinylamine With 1,1-Dinitroethane (a)Fifty milliliters of methanol containing 1.1 grams polyvinylamine wascooled to between zero and five degrees centigrade and 3.06 grams of1,1-dinitroethane dis solved in 30 milliliters of methanol decanted off,and the residue washedwith methanol and dried in a vacuum desiccator for30 hours. The product burned well leaving little ash. I

(b) Seven-tenths gram of polyvinylamine was dissolved in ethanol, thesolution placed in a beaker, and 0.5 gram of 1,1-dinitromethane addeddropwise with stirring. The alcohol was allowed to evaporate off and adark brown plastic material obtained. It analyzed for 22.1 percent N ascompared to 25.5 percent calculated.

(c) The conditions were the same as in Example 20 (i). Two grams of1.1-dinitroethane was reacted with 0.5 gram of polyvinylamine. Theyellow precipitate obtained burned with an almost smokeless flame.

EXAMPLE 26 Condensation ofRolyvinylamine With Dinitl omethane (a) Fiftymilliliters of methanol containing 1.1 grams of polyvinylamine wasplaced in a 400-rnilliliter beaker and'the solution cooled to betweenzero and five degrees centigrade. To this solution was added 250milliliters of ether containing approximately 2.46 grams ofdinitromethane. A white precipitate formed, was filtered as, and theresidue washed with ether and methanol and finally dried for 24 hours ina vacuum desiccator. The product burned Well, leaving very little ash.

(b) In this experiment the same experimental conditions as in Example 20(i) were used. Five-tenths gram of polyvinylarnine was reacted with twograms of dinitromethane. A light yellow product was obtained whichburned very well and left only a little ash.

EXAMPLE 27 Preparation of Poly-N-Vinyl- -Nitraphenylurea CH2--CH-CieHsNCO 11111: n

otmNnooNn-en HNO: OH:

' in a' glass-stoppered bottle and eight grams of phenyl isocyanateadded thereto. The bottle was stoppered and shaken vigorously. A whiteprecipitate was formed, washed with ether, then with water, and dried.This method is preferred to (a) since the time for the leaching processis shortened.

(c) Twenty-five milliliters of fuming nitric acid was placed in a250-milliliter Erlenmeyer flask and cooled to zero degrees centrigrade.Eight-tenths gram phenylurea derivative from (a) or (b) was added insmall amounts while maintaining the temperature between zero and fivedegrees centigrade. After addition was complete, the solution wasallowed to warm to room temperature and stand overnight. The nitrationsolution was then poured into cold water with stirring. A tanprecipitate was obtained, washed with distilled water, and dried in avacuum desiccator. The product analyzed for 21.35 percent N as comparedwith 25.59 percent N calculated.

(d) Two grams of poly-N-vinyl-N'-phenylurea was added to 40 millilitersof fuming HNO at room temperature. The mixture was maintained at 70degrees centigrade for 20 minutes, the'solution then filtered, cooled,and poured into ice-water. A yellow product was obtained which burnedfairly well. Nitrogen analysis gave 21.90 percent as compared to 25.32percent calculate-d.

(e) One gram of nitrated product from (d) was added to 80 milliliters ofmixed acid (85 percent concentrated H 80 percent concentrated HNO Themixture was heated for one hour at 85-90 degrees centigrade, thesolution filtered, cooled, and poured into ice-water. A light tanprecipitate was obtained which analyzed for 21.88 percent N as comparedto 25.32 percent calculated. This product burned well.

(f) One gram of the poly-N-vinyl-N'-phenylurea was added in smallamounts to 50 milliliters of fuming HNO at room temperature. The mixturewas allowed to stand for several hours at this temperature and was thenheated .on a steam bath for four hours at 50-60 degrees centigrade.

The solution was filtered and poured onto ice, whereupon a brownprecipitate formed. It was washed vwell with water, dried in a vacuumdesiccator, and found to burn well.

(g) Five-tenths gram of the phenylurea was dissolved in concentrated H80 and 30 milliliters of fuming nitric acid added dropwise to thesolution. The temperature rose to 35 degrees centigrade. It was thenfiltered and poured on ice. A yellow precipitate of the poly-N-vinyl-N'-nitrophenylurea was obtained.

was added dropwise while the temperature was kept below zero degreescentigrade. The solution was kept at this temperature for four hours andthen allowed to warm to room temperature overnight. The solution wasfiltered and poured on ice. A yellow gummy precipitate of thepoly-N-viny1-N'-nitrophenylurea was obtained.

The propellants of the present invention are, as previously stated,useful in the production of the impelling force for jet propulsionmotors. The invention thus provides novel solids combining fuel and allthe elements required for its combustion which can be used withoutexploding but with the production of great power.

These propellants are especially suited for use in rocket jet engines,which ordinarily comprise a combustion chamber where the fuel iscombusted and one or more exhaust nozzles leading from the chamber tothe atmosphere. Use of the self-combustible compositions of the presentinvention as charges in such motors is advantageous in that storage andfeed systems for an oxidizing element are eliminated, with subsequentreduction of weight, a matter of great importance in aircraft. As aconsequence of the saving in weight, a great gain in the ratio of totalimpulse to total weight is also realized. The substances are moreoverrelatively stable under a variety of conditions and hence safer thanmany compositions heretofore proposed, while at the same time beingcapable of generating great power upon decomposition.

The nitro plastic propellants will not spontaneously ignite in a coolmotor which allows a highly desirable safety factor. Accordingly, somemeans should be associated with the combustion chamber for ignition ofthe charge therein. Such suitable ignition or starting device may be aheating element located at the periphery of the combustion chamber, orsome other ignition mechanism, such as an electric are, or an auxiliaryflame introduced at a suitable place in the combustion chamber andcaused to operate at the moment of starting. Such rocket jet engines areknown in the art, as are suitable firing or ignition mechanisms valuabletherein. The propellant is merely secured in place in the combustionchamber, the ignition mechanism actuated and the propelled vehiclelaunched and/or maintained in motion by development of thrust bydecomposition of the propellant. Numerous other advantages of operationand result accrue to the use of these novel propellants, such assimplicity of construction and operation of the jet-motor, predeterminedconstancy of available energy, non-corrosive effects on equipment,higher specific impulse with relatively low combustion and exhausttemperatures, and the like, additional advantages being immediatelyapparent to one skilled in the art.

Various modifications may be made in the invention without departingfrom the spirit or scope thereof and it is to be understood that I limitmyself only as defined by the appended claims.

I claim:

1. The method of producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing component of ajet-type motor, which includes: polymerizing together a phenylenediaminewith an alkylene dibromide, and containing up to three carbon atoms, bycontacting the reagents together at a temperature below degreescentigrade, but at least at that temperature at which reaction occurs,and thereafter nitrating the polymer thus-produced by contacting saidpolymer with fuming nitric acid in an amount and time sufficient tointroduce enough nitro(NO groups into the molecule to afford sufncientoxygen present in the molecule to convert at least all of the carbon tocarbon monoxide and one-third of the hydrogen to steam upon combustionof the polymer.

2. A method of producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing component of ajet-type motor, which includes: polymerizing together a phenylenediaminewith phosgene by contacting the reagents together, and thereafternitrating the polymer thus-produced with sufiicient fuming nitric acidfor a period of time to introduce sufficient nitro(NO groups into thepolymer molecule to afford sufficient oxygen present in the molecule toconvert at least all of the carbon to carbon monoxide and one-third ofthe hydrogen to steam upon combustion of the polymer.

3. The method of producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing component of ajet-type motor, which includes: contacting a phenylenediamine, withethylene oxide, thereby to cause a polymerization reaction andthereafter nitrating the polymer thus-produced by contact with fumingnitric acid in an amount and time suflicient to introduce enoughnitro(NO groups into the polymer molecule to afiord suflicient oxygenpresent in the molecule to convert at least all of the carbon to carbonmonoxide and one-third of the hydrogen to steam upon combustion of thepolymer.

4. The process for producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing component of ajet-type motor, which includes: contacting ethylene diisocyanate withethylenediamine, to produce a polymeric material, and subsequentlycontacting said polymeric material with fuming nitric acid inamonnt andtime suflicient to introduce two nitro groups into each unit of saidpolymer, and separating the nitrated polymer thus-produced.

5. A method for producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing component of ajet-type motor, which includes: contacting meta-phenylenediamine withethylene diisocyanate to produce a polymeric material, and subsequentlycontacting said polymeric material with nitric acid in an amount andtime suflicient to introduce three nitro groups onto the phenyl ring andtwo nitro groups onto the nitrogen atoms of each unit of the polymericmaterial, and separating the polymer thus-produced.

6. The method of producing a substantially stable combustible nitroplastic adapted for use as the major thrust-producing component of ajet-type motor, which includes: nitrating a polymer selected from thegroup consisting of (A) an alkylene diamine containing from 2 to 6carbon atoms in the molecule, polymerized with an alkylene diisocyanate,(B) a phenylenediamine polymerized with an alkylene diisocyanate, (C) aphenylenediamine, polymerized with an alkylene dibromide containing upto 3 carbon atoms, (D) a phenylenediamine polymerized with phosgene, and(E) a phenylenediamine polymerized with ethylene oxide, by contactingsaid polymer with fuming nitric acid in an amount and for a timesuflicient to introduce into said polymer enough oxygen to convert atleast all the oxygen to carbon monoxide and one third of the oxygen tosteam upon combustion of the polymer.

7. The method of producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing compound of ajet-type motor, which includes: contacting an alkylene diaminecontaining from 2 to 6 carbon atoms in the molecule, with an alkylenediisocyanate, thereby to cause a polymerization reaction, and thereafternitrating the polymer thus-produced by contact with fuming nitric acidin an amount and for a time sufficient to introduce enough nitro (N0groups into the polymer molecule to afiord sufficient oxygen present inthe molecule to convert at least all of the carbon to carbon monoxideand one-third of the hydrogen to steam upon combustion of the polymer.

8. The method of producing a substantially stable combustible nitroplastic adapted for use as the major thrustproducing component of ajet-type motor, which includes: contacting a phenylenediamine with analkylene diisocyanate, thereby to cause a polymerization reaction, andthereafter nitrating the polymer thus-produced by contact with fumingnitric acid in an amount and time sufiicient to introduce enough nitro(N0 groups into the polymer molecule to afford suflicient oxygen presentin the molecule to convert at least all of the carbon to carbon monoxideand one-third of the hydrogen to steam upon combustion of the polymer.

9. The nitration production produced by the process of claim 6.

10. The nitration product produced by the process of claim 7.

11. The nitration product produced by the process of claim 8.

12. The nitration product produced by the process of claim 1.

13. The nitration product produced by the process of claim 2.

14. The nitration product produced by the process of claim 3.

References Cited in the file of this patent UNITED STATES PATENTS2,118,487 Burrows et al May 24, 1938 2,246,527 Melof June 24, 19412,275,923 Ross et al. Mar. 10, 1942 2,277,083 Dorough Mar. 24, 19422,310,943 Dorough Feb. 16, 1943 2,325,064 Lawrence July 27, 19432,384,049 Smith et al. Sept. 4, 1945 2,400,806 Bruson May 21, 19462,404,688 Bruson July 23, 1946 2,407,131 Bruson Sept. 3, 1946 2,408,252De Ganahl Sept. 24, 1946 2,419,043 Urbanski Apr. 15, 1947 FOREIGNPATENTS 856,335 France Mar. 18, 1940 512,987 Great Britain Oct. 2, 1939535,139 Great Britain Mar. 31, 1941 601,101 Great Britain Apr. 28, 1948UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,071,617 January 1, 1963 Henry B. Hass It is hereby certified thaterror appears in the above numbered patjent requiring correction andthat the said Letters Patent should read as corrected below.

Column 2, lines 45 to' 47 the formula should appear as shown belowinstead of as in the patent:

lOO=oxygen balance O line 63, for "considerable" read considered column13,

linesB to 10, strike out "The resulting solution was then rectified atreduced pressure, and, after the water had been removed, the followingfractions were'collectedz"; line 49, strike out "-NO column 18, line 12,for "3.5 grams" read f 33.5 grams column 26, after line 43, insert thefollowing:

2,287,093 Ellis June 23, 1942 Signed and sealed this 13th day of August1963.

' (SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Attesting OfficerCommissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION .atent No. 3,071,617 January 1 1963 Henry Bo Hass It ishereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, lines 45 to 47 the formula should appear as shown belowinstead of as in the patent: Y

lOO=oxygen balance R line 63, for "considerable" read considered column13,

lines 8 to 10, strike out "The resulting solution was then rectified atreduced pressure, and, after the water had been removed, the followingfractions were'collectedz"; line 49,

strike out "-NO column 18, line l2, for "35 grams" read 33.5 gramscolumn 26, after line 43, insert the following:

2,287,093 Ellis June 23, 1942 Signed and sealed this 13th day of August1963,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Qfficer Commissioner of Patents

6. THE METHOD OF PRODUCING A SUBSTANTIALLY STABLE COMBUSTIBLE NITROPLASTIC ADAPTED FOR USE AS THE MAJOR THRUST-PRODUCING COMPONENT OF AJET-TYPE MOTOR, WHICH INCLUDES: NITRATING A POLYMER SELECTED FROM THEGROUP CONSISTING OF (A) AN ALKYLENE DIAMINE CONTAINING FROM 2 TO 6CARBON ATOMS IN THE MOLECULE, POLYMERIZED WITH AN ALKYLENE DIISOCYANATE,(B) A PHENYLENEDIAMINE POLYMERIZED WITH AN ALKYLENE DIISOCYANATE, (C) APHENYLENEDIAMINE, POLYMERIZED WITH AN ALKYLENE DIBROMIDE CONTAINING UPTO 3 CARBON ATOMS, (D) A PHENYLENEDIAMINE POLYMERIZED WITH PHOSGENE, AND(E) A PHENYLENEDIAMINE POLYMERIZED WITH ETHYLENE OXIDE, BY CONTACTINGSAID POLYMER WITH FUMING NITRIC ACID IN AN AMOUNT AND FOR A TIMESUFFICIENT TO INTRODUCE INTO SAID POLYMER ENOUGH OXYGEN TO CONVERT ATLEAST ALL THE OXYGEN TO CARBON MONOXIDE AND ONE THIRD OF THE OXYGEN TOSTEAM UPON COMBUSTION OF THE POLYMER.